Today I’m going to get into the article behind a story that has been doing the rounds on Facebook recently. The headline claims that Science (with a capital S) has discovered how psychopaths drink their coffee, the accompanying picture is a strong, black cup of coffee. It’s a great click bait headline inspiring mock righteousness and indignation from all areas of the coffee spectrum. While this seems a frivolous topic (and the story I read certainly made it out to appear that way) the original study is situated in a broader area of personality research which seeks to find connections between taste preferences and individual personality traits.
Individual differences in bitter taste preferences are associated with antisocial personality traits by Christina Sagioglou and Tobias Greitemeyer from the University of Innsbruck in Austria.
Taste preferences are mainly believed to serve evolutionary needs (sweet foods often have the high calories needed for survival, while bitter foods often indicate toxic substances). But beyond these most basic needs, the food we are drawn to is influenced by many other things. The first taste of coffee or beer, for many people, is disgusting, but over time, people can grow to enjoy it. But this involves a period of adjustment, where one must forgo one motivation (that of pleasant taste) to experience another (social, neurochemical, or health related). Sagioglou and Greitemeyer wondered if it was a certain type of personality that persisted with bitter foods in order to gain a taste for them.
Several research studies suggest that personality traits can predict what food people choose to eat. People who have a high sensation seeking personality (think people who are always busy and trying new things) tend to prefer spicy food and foods high in caffeine more than those who don’t have that personality. Those who are very agreeable tend to like sweet foods compared to those who are less agreeable. Researchers have even been able to predict whether someone would select a glass of dry white wine over a sweet white wine based on how open to experiences they are. So there is definitely enough research to suggest personality and taste preference may go together.
This paper also raises an interesting possibility. They draw on past research that suggests, not only can personality traits influence taste preference, but continued exposure to particular tastes may increase corresponding personality traits. If a person was given something sweet they claimed to feel more agreeable. By contrast, when people were given bitter things to eat, they became hostile and argumentative! Sagioglou and Greitemeyer propose that prolonged exposure to bitter tastes could extend hostility into a personality trait.
Because of this background of research Sagioglou and Greitemeyer sought to determine if a preference for bitter tastes was associated with antisocial personality traits. They conducted two separate studies to explore their idea.
This paper consisted of two studies that explored the same question. Both were conducted on Amazon Mechanical Turk (MTurk) with sample sizes of 449 (214 female, 235 male) and 504 (247 female, 257 male) respectively. In both studies, participants were presented with a list of sweet, bitter, sour, and salty foods (included at the bottom of this entry) and were asked to rate how much they liked each food (from “dislike strongly” to “like strongly”). They were also asked how much they liked sweet, bitter, sour, and salty tastes in general.
In the second study participants were also asked to give a taste profile to each food presented. This was done to check whether the food categorised as bitter was actually perceived as bitter. Because a black shot of espresso is very different in taste to a Starbucks caramel latte, and they wanted to make sure they accounted for the differences in personal ratings. Indeed, when the researchers went back and looked at the foods they had labelled at ‘bitter’ only five of the original ten were rated as bitter foods and included in the analysis. These included: coffee, beer, radishes, tonic water, and celery.
For personality measures, participants gave details on their levels of verbal and physical aggression, anger, and hostility. They completed a measure of dark triad personality traits (Machiavelism, psychopathy, and narcissism) as well as a measure of sadistic tendencies. Finally, they completed a short personality measure which looked at the Big Five* personality traits (openness, conscientiousness, extraversion, agreeableness, and neuroticism). These measures were the same in both studies.
As predicted, the people who said they liked the bitter foods, as opposed to those who did not like them, were more likely to have higher scores of psychopathy, narcissism, everyday sadism, and aggression. They were also more likely to score low on the measure of agreeableness. These results were similar in the second study, with a couple of differences. The relationship between liking bitter foods and aggression disappeared, and one between bitter taste preferences and Machiavellianism became statistically significant.
When looking at particular antisocial personality traits, the researchers did find a small association between preferences for bitter foods, psychopathy, and sadism. And when I say small, I mean small. The statistics presented reveal that, in their sample, liking bitter food accounted for just over 1% of the variability in psychopathy and sadism scores in the first study, and psychopathy, sadism, narcissism, and Machiavellianism in the second study.
The difference in results between study 1 and study 2 is likely due to the re-evaluation of what actually was perceived as a bitter food by participants. While this adjustment didn’t make the relationship any stronger, it may have led to slightly cleaner results. If you are going to put stock in any of the relationships I would pay attention to the ones that were present in both study 1 and study 2.
What does all this mean?
This study isn’t perfect, and the researchers admit that. One thing they bring up is that using self-report to measure people’s taste preference has some flaws. People prepare foods in different ways, which affects the taste they personally experience. The researchers took this into consideration in the second study by collecting information on the personal taste profile people assigned to different foods and this did lead to eliminating half of what they originally categorised as bitter. For example, in the first study tea was grouped with the bitter foods, but when the researchers looked at what people actually thought tea tasted like, it did not receive a bitter rating. Many people add milk, sugar, or honey to their tea which drastically changes their experience of taste. One way to address this is to conduct a more rigorous controlled experiment. Giving participants a dropper of clear solution removes a host of other factors that can impact a person’s perception of taste**. However, I won’t criticise the self-report aspect of this study too harshly.
Another problem with self-report research is the social desirability bias. Even though these surveys are carried out anonymously there is a psychological cost to answering personal questions. As social creatures, humans are motivated to be liked by other people. In this particular study, this could dampen reporting on antisocial personality traits. The researchers also speculated if the linguistic association between the word “bitter” and negative personality traits may have also impacted likeability ratings of bitter foods.
However, I won’t criticise the self-report aspect of this study too harshly. The relationship between taste preference and personality is a relatively small body of research. While highly controlled experiments are the gold standard for understanding causal relationships, they are also expensive, time-consuming, and can easily be a huge waste of time if you don’t have a solid foundation of research to build upon. Research like the current study is important to test if a relationship is even worth exploring further. While the link between bitter taste preferences and anti-social behaviours doesn’t appear to be very strong the results suggest delving further into this link may be fruitful.
Back to the media
Now we come back to the scores of articles that have been claiming that “Psychopaths like to drink black coffee“, “How you drink your coffee ‘could point to psychopathic tendencies“, “People Who Order Coffee Black Are More Likely To Be Psychopaths“. One thing I couldn’t help thinking while I was reading the original research this latest click bait craze was based on was, “I wonder why no one is claiming liking radishes makes you a psychopath?”. Of course, the answer to this is that no one would click on that headline. I did see some that latched onto IPA’s and gin and tonic.
The buzz around this study (which is over 2 years old by the way) is exactly why I started this blog. The original research barely speaks of coffee, let alone it’s predictive value when it comes to psychopaths. It takes a very creative journalist to read the research I did and come to the conclusion that all those articles did. Even without an understanding of scientific methodology and statistical analysis Sagioglou and Greitemeyer presented a measured conclusion about their findings.
What you need to take away from this: Drinking black coffee does not make you a psychopath. The most gracious interpretation of these findings is that a preference for bitter tastes may be one of the many factors that are different between people who have more anti-social personality traits than others.
If you enjoy your coffee black, your chocolate dark, and your drinks heavy with the tonic continue as usual safe in the knowledge that you are not devoid of human emotion. However, if you prefer IPA’s I will continue to judge you.
*I talked about the Big Five personality traits in Are Grammar Police really that bad? and I’ve included a link below if you want to learn more about them.
**Research into the psychology of taste perception is amazing! You may think that it’s your taste buds that are responsible for how you experience flavour but there’s so much more. The sound of crunching can make things taste fresher. The colour of a liquid can affect the flavour of a drink. Even the words used to describe a food can make it taste it different. Let me know if you would like to hear more about this kind of research and I’ll add it to my list of future Research Ship destinations.
I apologise that today’s article is behind a paywall. I always do a thorough search to try and locate science that the general public can access because science should be free for everyone. I’ve attempted to give as much information as possible about the study, but if you have any further questions I would be happy to answer them in the comments.
List of Foods Used in the Study
Sweet: Candy; Caramel; Chocolate cake; Honey; Ice cream; Maple syrup; Pears; Raisins; Strawberries; Sugar.
Bitter: Beer; Celery; Coffee; Cottage cheese; Ginger ale; Grapefruit; Radishes; Rye bread; Tea; Tonic water.
Sour: Cranberries; Granny Smith apples; Lemons; Lemon drops; Limes: Lime sherbet; Plain yoghurt; Sauerkraut; Sour cream; Vinegar.
Salty: Bacon; Beef jerky; Caviar; Dill pickles; Green olives; Pretzels; Salt; Saltine crackers; Salty peanuts; Soy sauce.